The 2-hour postprandial blood glucose (postprandial blood sugar, PPBS) test reflects the metabolic response to a carbohydrate challenge.9 In normal individuals, the blood sugar returns to the fasting level within 2 hours.
In contrast, postprandial hypoglycemia appears to result from delayed or exaggerated response to the insulin secreted in relation to dietary blood sugar rise. It may occur as an early event in individuals with non-insulin-dependent diabetes mellitus (NIDDM, type II diabetes mellitus) or in individuals with gastrointestinal malfunction. Frequently, no cause is demonstrated and the hypoglycemia is considered "functional." Postprandial hypoglycemia differs from fasting hypoglycemia (i.e., hypoglycemia that occurs after 10 or more hours without food) in that the latter nearly always has pathological significance. It results from either overproduction of insulin or undermobilization of glucose and is most commonly seen in clients with tumors of the pancreatic cells (insulinoma), liver disease, and chronic alcohol ingestion.10
With advancing age, the speed of glucose clearance declines. Two-hour levels in persons who do not have diabetes and in those with negative family histories may increase an average of 6 mg/dL for each decade over age 30 years.11
Conventional Units | SI Units | |
---|---|---|
Blood | 120 mg/dL | 6.6 mmol/L |
Serum/plasma | 150 mg/dL | 8.3 mmol/L |
Conventional Units | SI Units | |
---|---|---|
Blood | ![]() | 6.6 mmol/L |
Serum/plasma | ![]() | 7.7 mmol/L |
Conventional Units | SI Units | |
---|---|---|
Blood | ![]() | 7.7 mmol/L |
Serum/plasma | ![]() | 8.8 mmol/L |
Note: Values may vary, depending on the laboratory method used.
Nursing Care Before the Procedure
General client preparation is the same as that for any test involving collection of a peripheral blood sample.
Two hours after the carbohydrate challenge is ingested, a venipuncture is performed and the sample is collected in either a gray- or a red-topped tube, depending on the laboratory performing the test. A capillary sample may be obtained in children and in adults for whom venipuncture may not be feasible. Capillary samples are also used when the test is performed for mass screenings. Note that in some instances a fasting blood sugar level may be obtained before the carbohydrate challenge.
Nursing Care After the Procedure
Care and assessment after the procedure are the same as for any study involving collection of a peripheral blood sample. Resume usual diet and activities.